The present invention relates to a lighting device for electronic apparatus and a lighting method for electronic apparatus, and in particular, to a lighting device for electronic apparatus and a lighting method for electronic apparatus capable of lighting a user""s operating section such as a keyboard of a portable personal computer in which power consumption is desired to be minimized.
In a portable personal computer, it is desired to possibly reduce power consumed by the computer. Since the portable personal computer is often used in a dark place or environment, a user""s operating section to be visually operated by the user, for example, a keyboard is required to be lighted. As well known, Japanese Utility Model Laid-Open Publication No. Hei 4-94467 describes such an electronic apparatus of power saving type. In the apparatus, a portion of backlight to illuminate a surface of a liquid crystal display (LCD) is employed to light an input device such as a keyboard. Since this known method directly uses the backlight, the quantity of light effectively used on the surface of the liquid crystal display is accordingly decreased. Namely, this is not sufficient for the power saving purpose.
It is desired to light the user""s operating section by using the backlight while completely saving power consumed.
It is therefore an object of the present invention to provide a lighting device for electronic apparatus and a lighting method for electronic apparatus which can light the user""s operating section by the backlight while completely saving power consumption.
Another object of the present invention is to provide a lighting device for electronic apparatus and a lighting method for electronic apparatus which can efficiently use part of light, namely, leakage of the backlight via an irregular reflection plate.
The objects are achieved as follows. In the description, reference numerals or the like are enclosed with parentheses to represent technical items. The reference numerals are the same as those assigned to technological items in at least one of embodiments in accordance with the present invention, and in particular, in embodiments of the present invention and drawings associated therewith. The reference numerals explicitly indicate a relationship and association of technical items between the claim and the embodiments. However, the present invention is not restricted by the relationship and association.
To achieve the object above, there is provided a lighting device for electronic apparatus comprising a liquid crystal display (LCD; 1), a light source (2) for emitting light for a backlight to illuminate said LCD, a reflection plate (5) for irregularly reflecting the light for the backlight, a light collecting optical system (6) for collecting leakage part of the light for the backlight, the leakage part leaking from said reflection plate to a rear surface side thereof, and a guide optical system (8) for guiding the light collected by said light collecting optical system toward an object to be illuminated. The leakage light which inevitably leaks from the reflection plate and which has been wasted can be efficiently used. It is also advantageous to positively increase the leakage light such that the quantity of leakage light thus obtained is more than that of the leakage light inevitably appearing in a natural condition.
In accordance with the present invention, the object to be illuminated is a keyboard (11), an ornament, or the like. To enhance decorative features, it is favorable to dispose a color changing section such as a filter between the light collecting optical system (6) and the object to be illuminated. The light collecting optical system (6) is desirably an aspherical lens (7) arranged on a rear surface side of the reflection plate (5). An aspherical lens is thin and has a short focal length. A plurality of aspherical lenses (7) are disposed to increase quantity of light collected.
In accordance with the present invention, the guide optical system (8) includes optical fiber(s) (9). The optical fiber(s) is/are extended to the object to be illuminated. The fibers having a high light guiding characteristic can guide the collected light up to the object to be illuminated. The leakage portion of light for the backlight can be efficiently used.
In accordance with the present invention, the object to be illuminated is a keyboard. The optical fibers are of side surface irregular reflection type and can illuminate a lot of arbitrary locations.
In accordance with the present invention, there is provided a lighting method for electronic apparatus, comprising the step of guiding, to an object to be illuminated, using the leakage light from an irregular reflection plate.